Category 4 functional safety (CAT4) compliance involves the ability to continue operating after two different failures in the safety circuits. Safe torque off (STO) functions ensure that no torque is applied by a driven motor during safe shutoff of a motor drive. Protection against a power supply exceeding the maximum intended output voltage (overvoltage protection) is important for CAT4 functional safety in motor drives as the redundant safe shutoff circuit for the PWM driver circuitry could be lost during an overvoltage event. Overvoltage protection to cover two concurrent faults is complicated for high performance motor drive control boards having multiple power rails that power associated downstream devices while implementing STO or other safety functions. Implementing safety functions such as STO enable and VCC as single channel elements requires high diagnostic coverage. Dual channel architectures are problematic. TVS diodes, fuses and other discrete components can be used to create redundant clamping circuits for each protected supply rail to protect against the possibility of multiple failures, but these solutions are costly in terms of circuit board space in motor drives. For two fault tolerant overvoltage protection of three supply rails, such a solution involves two clamping circuits in series on the output of each voltage rail. As motor drive control board sizes are reduced, conventional clamping circuit solutions are undesirable or not feasible.